Page 53
START
YES
NO
G776 IGNITION CONTROL TROUBLESHOOTING
−1 and −2 MODELS
Pilot lights but main valve will not come on
1993 Johnson Controls, Inc. Reprinted with permission.
Does spark
stay on for more than
5 seconds after pilot
lights?
Is 24VAC
between terminals
3 and ground?
Replace
control.
Correct
gas
pressure.
Correct
wiring.
Replace main
valve.
Is main
valve wiring securely
connected to terminals
3 and ground?
Is inlet
gas pressure per
manufacturer’s spec-
ifications?
Make sure sensor cable
and high voltage cable
are separated and not
wrapped around any
pipe or accessories.
Is main
valve wiring securely
connected to terminals
4 and ground?
Connect
securely.
Replace
sensor.
Is sensor
ceramic cracked?
Correct.
Correct.
Is sensor cable
grounded out?
Is sensor
or sensor connector
shorted to a metal
surface?
Does sensor cable
lack continuity
or good insulation?
Replace
cable.
Disconnect main valve lead from
terminal 3 and sensor cable from
terminal 4. Observing correct polarity,
connect DC microammeter between
terminal of sensor cable and terminal 4.
If system still fails, clean pilot
assembly, or replace flame
sensor, orifice, or control.
Is DC current
0.15 microamps or
greater?
Replace
control.
END
NO
NO
YES
NO
NO
YES
YES
FIGURE 58
YES
YES
YES
YES
NO
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YES
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YES
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